Lubricating grease compositions containing aliphatic sulfonic acid soap



United States Patet LUBRICATING GREASE COMPOSITIONS CON- TAININGALIPHATIC SULFONIC ACID SOAP William H. Brugmann, Jr., Milltown, JeffreyH. Bartlett, Westfield, and Arnold J. Morway, Clarktownship, UnionCounty, N. J., and Frederick Knoth, Jr., Palembang, Sumatra, Indonesia,assignors to Esso Research and Engineering Company, a corporation ofDelaware No Drawing. Application November 7, 1955 Serial No. 545,512

4 Claims. (Cl. 252-33) This invention relates to novel lubricatinggrease compositions. Particularly, the invention relates to lubricatinggrease compositions prepared by thickening a lubricating oil with a soapof an aliphatic sulfonic acid.

The present application is a continuation-impart of copendingapplication Serial No. 264,684, filed January 2, 1952, now abandoned bythe present inventors.

It has been found and forms the object of this invention thatlubricating grease compositions may be prepared by thickening alubricating oil to a grease consistency with an essentiallyoil-insoluble soap of a long chain aliphatic sulfonic acid having fromabout 10 to 20 carbon atoms in the aliphatic portion thereof. The greasecompositions so prepared have excellent smooth structures and highdropping points;

The olefins produced from the cracking of petroleum Wax or petrolatum ingeneral possess relatively long straight chains in which the olefinicgroup is near the end or the molecule. The large percentage of alphaolefins are obtained by the cracking of wax or petrolatum with some betaolefins also being formed. By the sulfonation of these olefins a productis obtained which has a sulfonic acid group near the end of a relativelylong straight chain. Other sources of olefins for the preparation ofthese long chain sulfonates are polymerized olefins from Fischersynthesis, polyethylenes, polypropylenes, polybutenes, and otherpolymeric olefins which give long straight chained molecules withrelatively little branching.

Various methods have been described in the literature for thepreparation of sulfonic acids from olefins. Such methods include theconversion of the olefin to a halide and then treating with sodiumsulfite. The olefinic halide may also be converted to a mercaptan andthe mercaptan oxidized to the sulfonic acid. Treatment of olefinicmaterials with S or ClSO H in the form of complexes with ether, dioxane,and the like has proved very success- 111 in the production of hydroxysulfonic acids or chlorosulfonic acids. The hydroxy sulfonic acids maybe dehydrated to yield alkene sulfonic acids. Similar products may beobtained by heating the chloro-sulfonic acids in which hydrochloric acidis split off. The straight sulfonic acids, and the chloro acids areoperable in the manufacture of the grease compositions of thisinvention. However, it is preferred to use the unsubstituted aliphaticsulfonic acids.

In general, the lubricating grease compositions of this invention areprepared by forming the metallic soap of the long chain aliphaticsulfonic acid and dispersing said 2 soap in a lubricating oil. This issimply accomplished by heating the mixture of the mineral oil and thesulfonate with agitation to a temperature above the melting point of thesulfonate and then allowing the heated mass to cool without stirring.

Additional properties may be incorporated intothe lubricating greases ofthis invention by admixing with minor amounts of various other additivematerials. For instance, high temperature properties are obtained bycodispersing the metal sulfonates with low molecular weight acid salts.Such materials as the metallic salts of acetic acid, furoic acid, andthe like may be added.

It is also within the concept of this invention to form a greasecomposition by thickening a lubricating oil with a mixture of themetallic soap' of a long chain sulfonic acid and any of the soapsordinarily used in grease-making, for example, high molecular weightsubstantiallysaturated fattyacid soaps. The incorporation of someadditional conventional soap adds to the smoothness of the grease aswell as improving the dropping point.

As was stated above, the long chain aliphatic sulfonic materialcontemplated by this invention contains from 10 to 20 carbon atoms permolecule. Although it is preferred that the aliphatic portion of thesulfonic acid be of straight chain configuration, some slight branchingis allowable. Especially preferred and contemplated in the preferredembodiment of this invention are those aliphatic sulfonic acids havingfrom 10 to 20 carbon atoms in a straight chain configuration.

Soaps of the sulfonic acids, as described above, are prepared fromalkalior alkaline-earth metals commonly used in the preparation of soapsfrom the conventional high molecular weight fatty acids. These includesodium, potassium, lithium, strontium, barium, calcium, and so forth.Sodium is preferable and is used in the preferred embodiment.These'metals are also employed to form the aforementioned salts of lowmolecular weight acids and soaps of conventional high molecular weightfatty acids.

The lubricating oil which serves as a base of the lubricating greasecomposition of this invention may be any of the lubricating oils knownto the art, either natural occurring or synthetic. Mineral lubricatingoils, preferred in the instant invention, having viscosities within therange of from about 35 to about 300 S. U. S. at 210 F. may be used.Those synthetic lubricating oils such as esters of dibasic acids (e. g.di-Z-ethyl-hexyl sebacate), esters of monobasic acids, ethers, glycols,glycol ethers, glycol esters, complex esters, or mixtures of the abovemay be used. Small amounts of petroleum resins may also be employed.

As Was mentioned above, it is within the concept of this invention toform a grease composition by dispersing in an oil a combination of themetallic soap of a long.

. Patented Sept. 30, wasv as complex soapthickeners'in combination withthe high molecular weight soaps. It is particularly preferred toincorporate in the sulfonic acid soap thickened lubricants suchmaterials as the metal salts of low molecular weight acids exemplifiedby acetic acid. Monocarboxylic acids containing 1 to 6 carbon atoms permolecule are pre ferred. Acetic acid is particularly preferred.

It has been found advantageous to thicken lubricating oil with fromabout 5% to 30% by weight based on the weight of the total compositionof the metallic soap of the aliphatic sulfonic acid; Inth'ose instanceswherein a combination of a conventional soap. and the sulfonate areused, from 10 to 90% (preferably '50 to 90%) of the sulfonate iscombined withabout 90 to 10% (preferably 10 to 50%) by weight of; theconventional soap. This combination ofsoaps will be employed in aconcentration of about 5 to 30% byweight; based on total composition. Ametal salt ofza low molecular weight acidic material may also becombined in order to obtain the advantages as outlined above, inconcentrations of from 0.5 to 15.0% by weight, preferably 2.0 to 10.0%by weight based on the total composition. Generally, it is preferred touse the metal salt of low molecular weight acidic material approximatelyin a 1:1 to 5:1 mol ratio pressure and 170 C. at 0.7 mm. pressure wassegregated This cracked petrolatum fraction had for sulfonation. abromine number of 64.3 c. e. q. Br g.

The sulfonation was carried out in a 3-liter'3 necked flask fitted witha stirrer, thermometer and dropping funnel. To the flask was charged 300g. of anhydrous ethyl ether. After cooling the ether to 5 C., 306 g. ofCISO H was added during 5 minutes at 5 C. to C. which resulted informing a ClSO H ether complex. While maintaining the ClSO H ethercomplex at C. to +2 C., 630 g. of cracked petrolatum (considered asapproximately C H with molecular weight of 252) was added during 20minutes. After all the olefin had been added the resulting mixture wasstirred for an additional 1 /2 hours during which the temperature wasallowed to rise to 25 C. The reaction product was then neutralized with25% NaOH solution after which 99% isopropyl alcohol was added so as toproduce a 50% alcohol solution in which the sulfonate was dissolved.This solution was then desalted with Na CO followed by separation of thesupernatant layer. Water was added to the supernatant layer to produceapproximately 50% isopropyl alcohol containing the sulfonate. Theisopropyl alcohol solution was then extracted 5 times with petroleumether to remove any unreacted olefin or other hydrocarbons. Evaporationof the petroleum ether yielded 243 g. of unreacted hydrocarbons.

The alcoholic solution containing the sulfonate was drum dried yieldingabrownish colored powder. This sodium sulfonate had a chlorine contentof 4.91%.

7 Example I 150 g. of the sodium soap of the long chain sulfonateprepared as described above were dispersed in 250 g. of an acid-treatedMid-Continent distillate having a visosity at 210 F. of about 40 S. U.S. hereinafter referred to as oil A. The mixture was heated to 100 F.with agitation. There was then added an aqueous solution of 100 g. ofsodium acetate and the mixture heated to 225 F. at which temperature thesoap became dehydrated.

Penetration, 77" F., mm./10:

Unworked 200 Worked (60 strokes) 240 Dropping point, F 380 Watersolubility soluble A. S. T. lVL-bearing lubrication test, hours (bearingoperating at 3600 R. P. M. and 250 F 204 Excellent lubricantno tendencyof grease to leak from bearing due to fluidization.

Example II 10.00% sodium soap of long chain sulfonate (as above) 5.00%hydrogenated fish oil acids 0.75% sodium hydroxide 84.25% oil A A of themineral oil and all of the fish oil acids were mixed in a fire-heatedgrease kettle and heated to F. with stirring. When the acid wascompletely melted an aqueous solution of the sodium hydroxide was added.When the acid neutralization or soap forming reaction was complete, thesodium sulfonate was added to the mixture and the mass heated to 225 F.for dehydration. When dehydration was complete the balance of themineral oil was added and the temperature raised to 260 F. It was thenallowed to cool to 200 F. with stirring and the result was an excellentsmooth product having the following inspections:

Penetration, 77 F., mm./l0:

Unworked 275 Worked (60 strokes) 275 Dropping point, F 354' Example IIIA portion of the grease as prepared in Example II above was admixed withan aqueous solution of sodium acetate so. that the resulting compositioncontained 2% of sodium acetate. The solution of sodium acetate wasdispersed in the grease and the mass was heated to 500' F. It was thenallowed to cool and further homogenized by working. The pertinentinspections of this grease sample are set out below:

Penetration, 77 F., mm./10:

Unworked 225 Worked (60 strokes) 265 Dropping point, P 425 Example IV20.0% sodium soap of long chain sulfonate (as above) to the standardgrease inspections this grease compositron gave the following results:

Penetration, 77 F., mm./

Unworked 300 Worked (60 strokes) 310 Dropping point, F. 320

Lubrication (AFBMA-NLGI Test) satisfactorily lubricates a 204 hearing at80-90 F. satisfactorily lubricates a 204 bearing at 150 F.

To summarize briefly, this invention relates to a lubricating greasecomposition prepared by thickening a lubricating oil by the addition ofsmall amounts of an essentially oil-insoluble metalic salt of alongchain aliphatic sulfonic acid having from 10 to carbon atoms in thealiphatic portion thereof. From about 5% to about 30% of the sulfonatehas been found operable although from about 8% to about 20% ispreferred. The grease compositions may also be prepared by dispersing ina mineral oil a combination of the long chain sulfonate and theconventional grease forming soaps. It is also contemplated to combinewith these grease combinations the salts of low molecular weightmaterials exemplified by sodium acetate, sodium furoate, and the like.

What is claimed is:

1. A lubricating grease composition comprising a major proportion of amineral lubricating oil thickened to a grease consistency with 5 to 30wt. of an oil-insoluble metal soap of a substantially straight chainaliphatic sulfonic acid containing from 10 to 20 carbon atoms permolecule in the aliphatic portion thereof said aliphatic sulfonic acidbeing the sole sulfonic acid present.

2. A lubricating grease composition comprising a major by weight of anoil-insoluble metal soap of a long chain aliphatic sulfonic acid havingfrom 10 to 20 carbon atoms in the aliphatic portion thereof ofsubstantially straight chain configuration said aliphatic sulfonic acidbeing the sole sulfonic acid present, and about 0.5 to 15.0% by weightof a metal salt of low molecular weight monocarboxylic acid, said metalbeing selected from the group consisting of alkali metals and alkalineearth metals.

3. A lubricating grease composition comprising a major proportion of amineral lubricating oil thickened to a grease consistency with from 5%to 30% by weight, based on the weight of the total composition, of acombination of an oil-insoluble metal soap of a long chain aliphaticsulfonic acid having from 10 to 20 carbon atoms per molecule and a metalsoap of a high molecular weight substantially saturated fatty acid saidaliphatic sulfonic acid being the sole sulfonic acid present and, saidcombination consisting of about 10 to of the soap of said sulfonic acidand about 90% to 10% of the soap of said fatty acid, said metal beingselected from the group consisting of alkali metals and alkaline earthmetals.

4. A composition according to claim 3 wherein said grease compositioncontains combined therein from 0.5% to 15.0% by weight of a metal saltof a low molecular weight monocarboxylic acid, said metal being selectedfrom the group consisting of alkali metals and alkaline earth metals.

References Cited in the file of this patent UNITED STATESPATENTS1,871,941 Arveson Aug. 16, 1932 2,394,790 Liehe Feb. 12, 1946 2,535,101Sproule et al. Dec. 26, 1950 2,540,534 Kolfenbach et al. Feb. 6, 1951

1. A LUBRICATING GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF AMINERAL LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH 5 TO 30WT. % OF AN OIL-INSOLUBLE METAL SOAP OF A SUBSTANTIALLY STRAIGHT CHAINALIPHATIC SULFONIC ACID CONTAINING FROM 10 TO 20 CARBON ATOMS PERMOLECULE IN THE ALIPHATIC PORTION THEREOF SAID ALIPHATIC SULFONIC ACIDBEING THE SOLE SULFONIC ACID PERCENT.